IMO Fuji's autoISO rule of 1/f was just way too slow for moving/human subjects. I got burned a few times from too slow of a SS photographing people with the 35/1.4 and their AutoISO, so I never used it.

Maybe useful for still subjects, but then again the XT1 has an ISO dial, just turn it and take the shot -- it's not like the subject is going anywhere.